Enthusiasm for folding-screen phones has been building for a decade. The tech press has been hyping flexible-screen technologies based on lab reports and futurist predictions. Only just now are companies preparing to ship actual products that use this technology.

The dual-screen idea has also been gaining purchase lately. This is driven mostly by the social media selfie craze, as well as the desperation of smartphone companies to differentiate their products in a sea of boring glass rectangles.

These ideas for increasing screen real estate appear to solve a longstanding challenge, which is that smartphone buyers want maximum screen sizes but minimum phone sizes. As we approach zero bezel and peak notch, the industry is wondering where to go next.

Unfortunately, the folding-screen and dual-screen ideas — while amazing in theory — are likely to disappoint enterprises, businesses and even consumer buyers.

I’ll tell you exactly why these phones won’t live up to the hype. But first, let’s take a look at what’s being announced, leaked or rumored.

Flexible-screen phones

Samsung’s Winner might eventually be branded as the Galaxy X or Galaxy F and may cost $2,000, according to rumors. The company has reportedly been rushing this device to market, but Winner probably won’t ship until next summer or later.

(Google is reportedly working with Samsung on a special or custom version of Android to support foldable-screen Samsung phones.)

Samsung may have wanted to be first to market with a folding-screen phone. But it’s probably too late. A California startup called Rouyu Technology (a.k.a. Royole) is now taking preorders for a $1,300 folding-screen phone called the FlexPai, which should ship in December. When the FlexPai unfolds, it provides the equivalent of a 7.8-inch tablet — the size of an iPad mini. When the device is folded, the screen wraps around the outside of the closed device, front and back. When opened, there’s another screen inside. The FlexPai is too large for most pockets.

Evan Blass, who has a long track record of accurately leaking future product news, said on Twitter this week that LG also plans to unveil a flexible-screen phone, at CES in January.

There’s no question that folding-screen phones are coming soon. And these early devices may have many imitators.

But bendy screens aren’t the only way to increase screen real estate on a smartphone.

Dual-screen phones

It’s clear that Microsoft is keen on dual-screen devices. The canceled Courier project from 10 years ago demonstrated the company’s interest.

“Andromeda,” which is rumored to be a dual-screen Windows 10 semi-phone, was probably postponed but may actually ship in the next year or two.

And last month Microsoft Research published a paper describing its idea for a smartphone cover with a secondary display. The company built a prototype for a Lumia 640 that came with a low-power, low-resolution eInk screen connected via Bluetooth that could provide additional information for Windows Phone apps. (Microsoft has apparently been working on this for a while.) The project also flirted with the idea of an eInk touch smartphone cover that functions as a keyboard.

In the paper, Microsoft researchers wrote something telling: “One limitation raised by users was the monochrome nature of the Display Cover; today’s consumers expect full color displays. We believe this could be addressed in future with the use of color bi-stable displays.”

A Chinese company called Nubia (a former subsidiary of ZTE) is set to release a phone called the Nubia X. The phone has a second, color display on the back, mainly for taking selfies with the better, rear camera. The implementation appears relatively elegant, with the screen more or less blending into the case. The Nubia X is planned for China only.

The Nubia X is similar in concept to an Australian product called the DigiCase, from a startup of the same name. The DigiCase is an app-controlled case that gives you a rear screen for taking selfies with your phone’s good camera. (It also contains a battery for extending the phone’s battery life.)

Other smartphone makers and case makers have announced or shipped options for adding another screen to the back of a smartphone.

More screen? What’s not to love?

Why folding-screen and dual-screen phones won’t thrill

In theory, folding-screen and dual-screen phones should be amazing. However, the technology isn’t ready to meet user expectations in enterprises, or even in the consumer marketplace.

Here are the seven reasons why folding-screen and dual-screen phones won’t appeal to the overwhelming majority of smartphone buyers:

Cost. The rumored $2,000 starting price for the Samsung folding-screen phone says a lot. The FlexPai isn’t cheap either. Extra screens add a monstrous additional cost to the phone. Ordinary phones are already pushing the upper boundaries of what buyers will pay. Folding screens push well past the boundaries. Even rear screens add an additional cost that most buyers don’t want to pay.

Battery life. A smartphone’s screen is one of the biggest drains on a phone’s battery, if not the biggest of all. All that extra screen real estate will add thickness to the phones, and the batteries needed to power all those screens will make them thicker still. While extra screen space helps with the screen problem, it exacerbates the battery problem.

Screen damage. With today’s technology, folding screens get creases and bends at the point of bending. And every time the screen is bent, it weakens, shortening the functional life of a very expensive device. And if the screen is on the outside, as with the screen on the FlexPai, the fragile screen is exposed to damage with no obvious way to add a protective case. With screens on both sides of the phone, just putting your phone down will accelerate damage.

Inelegant design. Folding screens, and all known dual-screen solutions with the exception of the Nubia X, are ugly, inelegant and clunky looking. But even the Nubia phone uses a low-resolution screen on the back, which isn’t great.

Size and bulk. Apple keeps making phones thinner, lighter and with smaller bezel sizes. The flexible-screen and dual-screen phones go in the opposite direction. Flexible screens don’t fold with a crease, but with a rounded gap. Inevitably, when closed, they will be several times thicker than standard modern smartphones. The FlexPai can’t even fit in a pocket. The whole point of the smartphone is that it fits in pockets.

Lack of apps. Android has always suffered from a fragmentation problem. Flexible-screen phones apparently require a custom OS and almost certainly will demand custom apps to take full advantage of the screens. A tiny percentage of buyers is likely to get them, so the app ecosystem for supporting apps will probably be tiny as well.

Better alternatives. There are multiple alternatives for adding mobile screen real estate. Tablets are cheap. Phones plug into TVs and monitors. And giant-screen “phablets” are available. For the selfie crowd, it makes far more sense to optimize the front-facing camera or cameras than it does to add a second screen for self-viewing while taking selfies with the rear camera. Google’s new Pixel 3 line shows the utility of having a wide-angle second lens for selfies, plus AI to create portrait-mode bokeh effects for selfies taken with the front-facing camera. Better front-facing cameras are far more cost-effective, battery-saving and size-and-weight-reducing than second rear screens.

So get ready for the hype. Over the next couple of years at least, we’ll see numerous new smartphone products that use flexible screens or offer a second screen.

Despite years of anticipation and buildup, the practical reality of these phones will prove unappealing. The same tech journalists who hyped the concepts will pan the products.

The dual-screen devices will die — and the folding-screen phones will fold.

Top image: The FlexPai will likely be the first flexible-screen phone to market.